Coagulant effects of black snake (Pseudechis spp.) venoms and in vitro efficacy of commercial antivenom

• Published in: Toxicon (Oxford) 2011-09, Vol.58 (3), p.239-246
• Main Authors: Lane, J., O’Leary, M.A., Isbister, G.K.
• Format: Article
• Language: English
• Subjects: Acetophenones - pharmacology; Animal poisons toxicology. Antivenoms; Animals; antibodies; anticoagulant activity; anticoagulants; Anticoagulation; Antivenins - pharmacology; antivenoms; Biological and medical sciences; Blood Coagulation - drug effects; Coagulopathy; cross reaction; Cross Reactions; Elapid Venoms - immunology; Elapid Venoms - toxicity; Hematologic and hematopoietic diseases; Humans; immunoglobulin G; Medical sciences; Notechis scutatus; patients; Phospholipase A2; Phospholipases A2 - metabolism; Platelet diseases and coagulopathies; Pseudechis; Pseudechis australis; Pseudechis porphyriacus; Rabbits; snakes; Toxicology; Venom; venoms
• ISSN: 0041-0101; 1879-3150
• DOI: 10.1016/j.toxicon.2011.05.020

The coagulant effects of Australasian black snakes (Pseudechis spp.) are poorly understood and differ to the procoagulant venoms of most dangerous snakes in Australia. This study aimed to investigate in vitro coagulant effects of Pseudechis venoms and the efficacy of commercial black snake antivenom (BlSAV), tiger snake antivenom (TSAV) and specific rabbit anti-snake IgG to neutralise these effects. Using a turbidimetric assay, all six Pseudechis venoms had anticoagulant activity, as well as phospholipase A2 (PLA2) activity. Inhibition of PLA2 activity removed anticoagulant effects of the venoms. Pseudechis porphyriacus was unique and had procoagulant activity independent of PLA2 activity. Both BlSAV and TSAV completely inhibited the coagulant and PLA2 activity of all Pseudechis venoms. PLA2 activity was also inhibited completely by p-Bromophenacyl bromide (pBPB) and partially by specific anti-N. scutatus IgG antibodies. Anti-N. scutatus IgG also completely inhibited anticoagulant activity of Pseudechis venom. All Pseudechis venoms showed immunological cross reactivity with specific anti-snake IgG antibodies to P. porphyriacus, Pseudechis australis and Notechis scutatus. Pseudechis venoms have in vitro anticoagulant activity that appears to be attributable to PLA2 activity. Both antivenoms inhibited anticoagulant and PLA2 activity at concentrations below those occurring in patients treated with one vial of antivenom. There was cross-neutralisation of Pseudechis venoms and N. scutatus antibodies that might be attributable to immunological similarities between the venoms. ► Six Pseudechis (black snake) venoms have anticoagulant and PLA2 activity. ► P. porphyriacus (red-bellied black snake) was unique and had procoagulant activity. ► Black snake and tiger snake antivenom inhibited coagulant and PLA2 venom activity. ► There was cross-neutralisation of Pseudechis and N. scutatus (tiger snake) venoms.